For example, when manufacturing a semiconductor, it is required to supply a mixed gas containing a material gas, which is produced by vaporizing a liquid or solid material, into a deposition apparatus at a predetermined concentration and flow rate.
The material gas is produced by introducing a carrier gas into the material stored in a tank to, for example, bubble the material for the vaporization. The material gas produced by the vaporization in the tank is mixed with the carrier gas to produce the mixed gas, and the mixed gas flows through a gas supply line connected from the tank to the deposition apparatus. The concentration and flow rate of the mixed gas are conventionally controlled to predetermined values by a gas control system that is provided in the gas supply line and includes a concentration sensor and a mass flow controller (see Patent Literature 1).